Obesity, Metabolism and the Circadian Rhythm

The Nobel prize in medicine and physiology has been awarded this year to three American scientists for discovering the underlying molecular mechanism of biological clocks. Biological clocks allow us to follow a circadian rhythm that allows numerous body functions to synchronize to the light-dark cycle on earth. Biological clocks control our sleep pattern, as well as metabolism, energy expenditure, and body weight. A mismatch between these internal clocks and our lifestyle or external environment results in disease and lack of well being. Experiments in mice showed that altering feeding time from dark to light phase results in weight gain. Furthermore, mice fed a high fat diet ad libitum develop obesity. Mice fed the same diet over an 8-hour period only restricted to the dark phase did not gain weight. In addition, genetically engineered mice that lack the circadian clock in adipocytes tend to consume more calories during the light phase and develop obesity. Interestingly, the overall calorie intake does not change in these mice. These experiments show that a temporal change in feeding disrupts energy balance resulting in obesity.

When you eat may be as important as what you eat. More than 90% of our patients at Houston weight Loss Surgery Center skip breakfast. Patients who skip breakfast graze on food throughout the night because of decreased satiety and increased hunger. Studies in humans have shown that overweight individuals lose more weight when consuming most of their calories in the morning. Furthermore, fasting glucose and blood triglyceride levels tend to decrease by consuming a big breakfast and a small dinner without changing the total daily calorie intake. Indeed, we recommend to our patients to avoid carbohydrate consumption at dinner time as it serves no other purpose than fat accumulation. Conversely, a breakfast rich in complex carbohydrates provides excellent hunger control throughout the day and increased satiety around dinner time.

There is strong evidence that link circadian rhythms and energy metabolism. Every organ in the body has a biological clock that works synchronous with the master clock in the brain. Future research will unravel more details about this delicate and complex rhythmic physiology. Living in synchrony with these internal clocks optimizes your metabolism and may help you lose excess weight or prevent obesity from developing.